Bob’s CTD work on this cruise was the most comprehensive CTD survey of the Chukchi Sea ever done, and the first to go so far north so early in the season. His water profile data about temperature, salinity, nutrients, and currents is all new and gives the scientists a much better idea of how the currents change seasonally in the Chukchi Sea. Chris and Ken learned a lot about light transmission through sea ice, light absorption by ice algae within the ice, and what kind of light and ice conditions are not enough to start a plankton bloom. For example it turns out that the ice has to stop freezing and start melting before a bloom can start, even if there is enough light, and that is what didn’t happen for us. They also made some new discoveries about ice permeability to salt vs fresh water and how fresh water melt ponds are able to sit on top of the ice without soaking through. Kevin never got to see the plankton blooms he was hoping for, but at least now they all have a much better idea of the under ice conditions before the blooms start and also a better idea of what it might take to actually start one. And a reason to go back again another year!
Wednesday, July 16, 2014
In the end we never did actually find an under ice plankton bloom like the ones that were accidentally discovered in 2010 and 2011, and the melt ponds that we were looking for only just started to appear in the last few days of the cruise. Research cruises have to be planned far in advance and there’s just no way to predict exactly when melt ponds will form or blooms will start in any given year. At the beginning of this cruise the scientists were worried that we might have come too late and wouldn’t be able to get far enough north fast enough to get ahead of the blooms, but in the end it turned out that we were a little too early and once we got into the ice the snow melt and melt pond formation we were waiting for didn’t happen in time for us to see them. That’s how it goes though and we did get one of the first and most thorough looks ever at the Chukchi Sea in pre-bloom winter conditions, so it’s not as if it was a wasted effort.